Closed-loop drilling system using a high-speed communications network

ABSTRACT

A closed-loop downhole drilling system is disclosed that includes a high-speed communications network, comprising multiple nodes, integrated into a downhole drilling string. The high-speed communications network supports data transmission rates far exceeding data rates of mud pulse telemetry systems. Sensors, located at a selected points along the downhole drilling string, are operably connected to the nodes and transmit data through the communications network corresponding to conditions sensed downhole. A control module receives the sensor data through the communications network and automatically adjusts uphole or downhole-drilling parameters in response thereto.

U.S. GOVERNMENT INTEREST

This invention was made with government support under Contract No. DE-FC26-01NT41229 awarded by the U.S. Department of Energy. The government has certain rights in the invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to oil and gas drilling, and more particularly to apparatus and methods for implementing a closed-loop drilling system using a high-speed communications network.

2. Background

The goal of accessing data from a drill string has been expressed for more than half a century. As exploration and drilling technology has improved, this goal has become more important in the industry for successful oil, gas, and geothermal well exploration and production. For example, to take advantage of numerous advances in the design of various tools and techniques for oil and gas exploration, it would be beneficial to a drill operator to have real time downhole data such as temperature, pressure, inclination, salinity, etc., to optimize drilling parameters.

Various attempts have been made to devise a successful high-speed system for accessing drill string data from downhole components. However, due to the complexity, expense, and unreliability of such systems, many such attempts have failed to achieve significant commercial acceptance or implementation. As a result, most drill operators continue to use very slow transmission technologies by today's standards. For example, many drill operators continue to use mud pulse telemetry to transmit data between downhole sensors and the surface. In mud pulse telemetry systems, data is transmitted by way of pressure pulses transmitted through drilling fluid, such as drilling mud. Mud pulse telemetry is often limited to data rates of 1 to 4 bits per second, which creates severe limitations to the types and quantities of data that can be transmitted uphole.

Due to these constraints, various drilling technologies install data processing hardware downhole, near downhole tools and sensors, to process data gathered therefrom. This raw data is processed and condensed into “answers” or “conclusions” represented by a relatively small number of data bits. These bits are then transmitted uphole using mud pulse telemetry where an operator may analyze the information and take responsive action. Nevertheless, most raw data gathered from sensors and other downhole devices cannot reach the surface due to the bottleneck created by mud pulse telemetry. Moreover, the downhole environment may limit downhole processors. For example, high temperatures, vibration, corrosive elements, and the like, may limit the performance and sophistication of downhole processors. In addition, slow data rates of mud pulse telemetry systems may make reprogramming of downhole circuitry very time consuming.

The bottleneck created by mud pulse telemetry and other transmission systems may have other implications as well. For example, various efforts have been directed to creating closed-loop drilling systems that automatically adjust drilling parameters in response to data gathered from downhole sensors. In general, closed-loop systems use sensor feedback to adjust parameters without manual input from an operator. The goal of closed-loop drilling systems is to change drilling parameters rapidly and dynamically in response to changing downhole conditions. Closed-loop systems may be self-regulating, accurate, and reduce the need for human supervision. This may reduce the expense of operating a drill rig and the time needed to tap into oil and gas bearing reservoirs.

Nevertheless, close-loop drilling systems are severely limited by mud pulse or other telemetry systems. For example, due to the limited bandwidth of current telemetry systems, control and processing hardware is typically installed downhole near tools and sensors. As was previously explained, control and processing hardware may be limited in a downhole environment. Moreover, closed-loop adjustments may be primarily limited to downhole components, and significant amounts of data may not reach the surface where it can be analyzed and logged to further optimize drilling.

Thus, what are needed are apparatus and methods for improving the performance and sophistication of closed-loop drilling systems using a high-speed communications network.

What are further needed are apparatus and methods for transmitting large amounts of data to the surface for logging, analysis, and drilling parameter adjustments.

What are further needed are apparatus and methods for relocating closed-loop controls and processing from downhole tools to surface hardware.

SUMMARY OF THE INVENTION

In view of the foregoing, apparatus and methods in accordance with the invention are directed to implementing a closed-loop drilling system using a high-speed communications network that significantly increased the performance and capability of closed-loop systems. Apparatus and methods in accordance with the invention are further directed transmitting large amounts of data to the surface for logging, analysis, and use for adjusting both uphole and downhole drilling parameters. Moreover, apparatus and methods in accordance with the invention are directed to relocating processing capability from downhole tools to the surface where significantly greater processing power is available.

Consistent with the foregoing, and in accordance with the invention as embodied and broadly described herein, a closed-loop downhole drilling system is disclosed in one embodiment of the present invention as including a high-speed communications network integrated into a downhole drilling string. The high-speed communications network supports data transmission rates far exceeding traditional mud pulse telemetry systems. The communications network includes multiple nodes installed at selected intervals along the downhole drilling string. Sensors, located at a selected point along the downhole drilling string, are operably connected to the nodes and transmit data through the communications network. A control module, in operable communication with the communications network, receives the sensor data and automatically adjusts uphole or downhole-drilling parameters in response to the data.

Various different types of sensors may be used in making drilling parameter adjustments. For example, in selected embodiments, sensors may include formation coring tools, mud logging devices, fluid flow rate sensors, RPM sensors, torque sensors, pore fluid sensors, permeability sensors, density sensors, resistivity sensors, induction sensors, sonic devices, radioactivity sensors, gamma ray tools, electrical potential tools, vibration sensors, magnetic field sensors, Hall-effect sensors, temperature sensors, accelerometers, imaging devices, seismic devices, caliper tools, pressure sensors, inclination sensors, azimuth sensors, surveying tools, navigation tools, MWD tools, DWD tools, LWD tools, GPS devices, load sensors, displacement sensors, kick detection sensors, fluid sampling devices, tool-wear sensors, or the like.

Data from these sensors may be used to optimize drilling performance. For example, the control module may, in response to the data, adjust or optimize various downhole drilling parameters though the network including but not limited to weight-on-bit, downhole motor RPM, downhole motor torque, drilling direction, drilling fluid jet direction, drilling fluid jet flow rate, drilling fluid flow rate, drilling fluid rheology, drill string jarring, kick control devices, drilling fluid pressure, or the like. Likewise, in other embodiments, the control module may adjust or optimize various surface drilling parameters such as weight-on-bit, drill string RPM, drill string torque, kick control, drilling fluid flow rate, drilling fluid rheology, drilling fluid pressure, or the like.

In selected embodiments, the control module is implemented by electronic hardware and software located above the ground's surface. In other embodiments, the control module may be integrated into the drill string at a selected point below the ground's surface, such as in the bottom hole assembly. Because of the high-speed capability of the communications network, raw data from any or all of the sensors located downhole may be transmitted uphole where the data may be analyzed and processed. Thus, very little data processing capability is needed downhole.

In another aspect of the invention, a method for implementing a closed-loop downhole drilling system may include installing multiple nodes at selected intervals along a downhole drilling string, where each of the nodes are capable of high-speed communication with one another. The method includes sensing conditions at selected points along the downhole drilling and communicating these conditions by way of data transmitted between the high-speed nodes. These nodes may be capable of transmitting data at speeds far exceeding data rates of traditional mud pulse telemetry. The data may be received and used to automatically adjust one or more uphole or downhole drilling parameters in response thereto.

In selected embodiments, the data may contain information corresponding to uphole or downhole conditions and measurements such as formation characteristics, drilling fluid rheology, drill string RPM, drill string torque, sonic measurements, radioactivity, electrical potential, vibration, magnetic field strength, Hall-effect field strength, temperature, acceleration, downhole dimensions, pressure, inclination, azimuth, drill string position, weight-on-bit, pressure kicks, fluid flow rates, tool conditions, or the like.

Likewise, in response to these conditions, downhole parameters may be automatically adjusted. These downhole parameters may include weight-on-bit, downhole motor RPM, downhole motor torque, drilling direction, drilling fluid jet direction, drilling fluid jet flow rate, drilling fluid flow rate, drilling fluid rheology, drill jarring, drilling fluid pressure, or the like. Likewise, uphole parameters that may also be adjusted include weight-on-bit, drill string RPM, drill string torque, kick control, drilling fluid flow rate, drilling fluid rheology, drilling fluid pressure, or the like.

In selected embodiments, the data may be processed or analyzed above the ground's surface. Thus, very little data processing capability is need below the ground's surface. In other embodiments, some data and corresponding adjustments may be processed below the ground's surface using control and processing hardware integrated into the drill string.

It should be noted that the term “operable communication” is meant to describe a network that can transmit data at a rate 1,000 bits per second. U.S. Pat. Nos. 6,670,880 and 6,717,501 are examples of two systems that can transmit data at such rates.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will become more fully apparent from the following description, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments in accordance with the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which:

FIG. 1 is a profile view of one embodiment of a drill rig and drill string in accordance with the invention;

FIG. 2 is a schematic diagram illustrating one embodiment of a downhole network in accordance with the invention, integrated into the drill string;

FIG. 3 is a schematic block diagram illustrating various types of hardware and software modules that may be included in a network node in accordance with the invention;

FIG. 4 is a schematic block diagram illustrating one embodiment of a closed-loop drilling system disclosed in the prior art;

FIG. 5 is a schematic block diagram illustrating one embodiment of a closed-loop drilling system using a high-speed communications network in accordance with the invention;

FIG. 6 is a schematic block diagram illustrating another alternative embodiment of a closed-loop drilling system using a high-speed communications network in accordance with the invention;

FIG. 7 is a flow chart illustrating one embodiment of a process used to implement a closed-loop drilling system in accordance with the invention.

FIG. 8 is a schematic block diagram illustrating one embodiment of a downhole network interfacing to various tools and sensors;

FIG. 9 is a schematic block diagram illustrating one embodiment of hardware and software components that may be included in a network node in accordance with the invention; and

FIG. 10 is a schematic block diagram illustrating one embodiment of a network packet in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of embodiments of apparatus and methods of the present invention, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of various selected embodiments of the invention.

The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. Those of ordinary skill in the art will, of course, appreciate that various modifications to the apparatus and methods described herein may easily be made without departing from the essential characteristics of the invention, as described in connection with the Figures. Thus, the following description of the Figures is intended only by way of example, and simply illustrates certain selected embodiments consistent with the invention as claimed herein.

Many of the functional units described in this specification have been labeled as modules, in order to more particularly emphasize their implementation independence. For example, modules may be implemented in software for execution by various types of processors. An identified module of executable code may, for instance, comprise one or more physical or logical blocks of computer instructions that may, for instance, be organized as an object, procedure, or function. Nevertheless, the executables of an identified module need not be physically located together, but may comprise disparate instructions stored in different locations which, when joined logically together, comprise the module and achieve the stated purpose for the module. For example, a module of executable code could be a single instruction, or many instructions, and may even be distributed over several different code segments, among different programs, and across several memory devices.

Modules may also be implemented in hardware as electronic circuits comprising custom VLSI circuitry, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. A module may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, or the like. Similarly, operational data may be identified and illustrated herein within modules, and may be embodied in any suitable form and organized within any suitable type of data structure. The operational data may be collected as a single data set, or may be distributed over different locations including over different storage devices, and may exist, at least partially, merely as electronic signals on a system or network.

Referring to FIG. 1, a drill rig 10 may include a derrick 12 and a drill string 14 comprised of multiple sections of drill pipe 16 and other downhole tools. The drill string 14 is typically rotated by the drill rig 10 to turn a drill bit 20 that is loaded against the earth 19 to form a borehole 11. Rotation of the drill bit 20 may alternately be provided by other downhole tools such as drill motors, or drill turbines (not shown) located adjacent to the drill bit 20.

A bottom-hole assembly 21 may include a drill bit 20, sensors, and other downhole tools such as logging-while-drilling (“LWD”) tools, measurement-while-drilling (“MWD”) tools, diagnostic-while-drilling (“DWD”) tools, or the like. Other downhole tools may include heavyweight drill pipe, drill collar, stabilizers, hole openers, sub-assemblies, under-reamers, rotary steerable systems, drilling jars, drilling shock absorbers, and the like, which are all well known in the drilling industry.

While drilling, a drilling fluid is typically supplied under pressure at the drill rig 10 through the drill string 14. The drilling fluid typically flows downhole through the central bore of the drill string 14 and then returns uphole to the drill rig 10 through the annulus 11. Pressurized drilling fluid is circulated around the drill bit 20 to provide a flushing action to carry the drilled earth cuttings to the surface.

Referring to FIG. 2, while continuing to refer generally to FIG. 1, in selected embodiments, a downhole network 17 may be used to transmit information along the drill string 14. The reader is referred to U.S. Pat. Nos. 6,670,880 and 6,717,501 issued to Hall et al., disclosing various embodiments of network hardware that can be used to implement a network 17 in accordance with the invention. These patents are herein incorporated by reference. The downhole network 17 may include multiple nodes 18 a-e spaced at desired intervals along the drill string 14. The nodes 18 a-e may be intelligent computing devices 18 a-e, such as routers, or may be less intelligent connection devices, such as hubs, switches, repeaters, or the like, located along the length of the network 17. Each of the nodes 18 may or may not have a network address. A node 18 e may be located at or near the bottom hole assembly 21. The bottom hole assembly 21 may include a drill bit 20, drill collar, and other downhole tools and sensors designed to gather data, perform various functions, or the like.

Other intermediate nodes 18 b-d may be located or spaced along the network 17 to act as relay points for signals traveling along the network 17 and to interface to various tools or sensors located along the length of the drill string 14. Likewise, a top-hole node 18 a may be positioned at the top or proximate the top of the drill string 14 to interface to an analysis device 28, such as a personal computer.

Communication links 24 a-d may be used to connect the nodes 18 a-e to one another. The communication links 24 a-d may consist of cables or other transmission media integrated directly into the tools comprising the drill string 14, routed through the central bore of the drill string 14, or routed externally to the drill string 14. Likewise, in certain embodiments, the communication links 24 a-d may be wireless connections. In selected embodiments, the downhole network 17 may function as a packet-switched or circuit-switched network.

To transmit data along the drill string 14, packets 22 a, 22 b may be transmitted between the nodes 18 a-e. The packets 22 b may carry data gathered by downhole tools or sensors to uphole nodes 18 a, or may carry protocols or data necessary to the function of the network 17. Likewise, some packets 22 a may be transmitted from uphole nodes 18 a to downhole nodes 18 b-e. For example, these packets 22 a may be used to carry control signals or programming data from a top-hole node 18 a to tools or sensors interfaced to various downhole nodes 18 b-e. Thus, a downhole network 17 may provide a high-speed means for transmitting data and information between downhole components and devices located at or near the earth's surface 19.

Referring to FIG. 3, a network node 18 in accordance with the invention may include a combination of hardware 29 and software providing various functions 30. The functions 30 may be provided strictly by the hardware 29, software executable on the hardware 29, or a combination thereof. For example, hardware 29 may include one or several processors 31 capable of processing data as well as executing instructions. The processor 31 or processors 31 may include hardware such as busses, clocks, cache, or other supporting hardware.

Likewise, the hardware 29 may include volatile 34 and non-volatile 36 memories 32 to store data and provide staging areas for data transmitted between hardware components 29. Volatile memory 34 may include random access memory (RAM), or equivalents thereof, providing high-speed memory storage. Memory 32 may also include selected types of non-volatile memory 36 such as read-only-memory (ROM), PROM, EEPROM, or the like, or other long-term storage devices, such as hard drives, floppy disks, flash memory, or the like. Ports 38 such as serial ports, parallel ports, or the like may be used to interface to other devices connected to the node 18, such as various sensors or tools located proximate the node 18.

A modem 40 may be used to modulate digital data onto an analog carrier signal for transmission over network cable or other transmission media, and likewise, demodulate the analog signals when received. A modem 40 may include various built in features including but not limited to error checking, data compression, or the like. In addition, the modem 40 may use any suitable modulation type such as ASK, PSK, QPSK, OOK, CW, PCM, FSK, QAM, PAM, PPM, PDM, PWM, or the like, to name a few. However, the choice of a modulation type may depend on a desired data transmission speed, the bandwidth capability of the network hardware, as well as unique operating conditions that may exist in a downhole environment. Likewise, the modem 40 may be configured to operate in full-duplex, half-duplex, or other mode. The modem 40 may also use any of numerous networking protocols currently available, such as collision-based protocols like Ethernet, token-based, or asynchronous transfer (ATM) protocols.

A node 18 may also include one or several switches 42, such as multiplexers. A switch 42 may filter, forward, and route traffic on the network. Multiplexers (and corresponding demultiplexers) may transmit multiple signals over a single communications line or a single channel. The multiplexers may use any known protocol to transmit information over the network 17, including but not limited to frequency-division multiplexing, time-division multiplexing, statistical time-division multiplexing, wave-division multiplexing, code-division multiplexing, spread spectrum multiplexing, or a combination thereof.

A node 18 may also include various downhole tools 46 and sensors 44. These tools 46 and sensors 44 may be integrated into the node 18 (i.e. share the same circuitry) or interface to the node 18 through ports 38. Tools 46 and sensors 44 may include devices such as coring tools, mud logging devices, pore fluid sensors, resistivity sensors, induction sensors, sonic devices, radioactivity sensors, electrical potential tools, temperature sensors, accelerometers, imaging devices, seismic devices, mechanical devices such as caliper tools or free point indicators, pressure sensors, inclinometers, surveying tools, navigation tools, or the like. These tools 46 and sensors 44 may be configured to gather data for analysis uphole, and may also receive data such as control signals, programming data, or the like, from uphole sources. For example, control signals originating at the surface may direct a sensor 44 to take a desired measurement. Likewise, selected tools 46 and sensors 44 may be re-programmed through the network 17 without extracting the tools from the borehole.

A drill string 14 may extend into the earth 20,000 feet or more. As such, signal loss or attenuation may be a significant factor when transmitting data along the downhole network 17. This signal loss or attenuation may vary according to the network hardware. For example, a drill string 14 is typically comprised of multiple segments of drill pipe 16 or other drill tools. As such, signal loss may occur each time a signal is transmitted from one downhole tool to another. Since a drill string may include several hundred sections of drill pipe 16 or other tools, the aggregate attenuation can be significant. Likewise, attenuation may also occur in the cable or other transmission media routed along the drill string 14.

To compensate for signal attenuation, repeaters 48, or amplifiers, may be spaced at selected intervals along the network 17. The amplifiers may receive a data signal, amplify it, and transmit it to the next node 18. Like amplifiers, repeaters 48 may be used to receive a data signal and retransmit it at higher power. However, unlike amplifiers, repeaters 48 may remove noise from the data signal. This may be done by demodulating the data from the transmitted signal and re-modulating it onto a new carrier.

Likewise, a node 18 may include various filters 50. Filters 50 may be used to filter out undesired noise, frequencies, and the like that may be present or introduced into a data signal traveling up or down the network 17. Likewise, the node 18 may include a power supply 52 to supply power to any or all of the hardware 29. The node 18 may also include other hardware 54, as needed, to provide other desired functionality to the node 18.

The node 18 may provide various functions 30 that are implemented by software, hardware, or a combination thereof. For example, the node's functions 30 may include data gathering 56, data processing 58, control 60, data storage 62, or other functions 64. Data may be gathered 56 from sensors 44 located downhole, tools 46, or other nodes 18 in communication with a selected node 18. This data 56 may be transmitted or encapsulated within data packets transmitted up and down the network 17.

Likewise, the node 18 may provide various data processing functions 58. For example, data processing may include data amplification or repeating 72, routing or switching 74 data packets transmitted along the network 17, error checking 76 of data packets transmitted along the network 17, filtering 78 of data, as well as data compression 79 and decompression. Likewise, a node 18 may process various control signals 60 transmitted from the surface to tools 46, sensors 44, or other nodes 18 located downhole. Likewise, a node 18 may store data that has been gathered from tools 46, sensors 44, or other nodes 18 within the network 17. Likewise, the node 18 may include other functions 64, as needed.

In selected embodiments, a node 18 may include a data rate adjustment module 86. The data rate adjustment module 86 may monitor network traffic traveling in both uphole and downhole directions. The data rate adjustment module 86 may optimize the network's settings and efficiency by adjusting the allocation of bandwidth for data traveling uphole and downhole. As is typical in most communication systems, data rates may be limited by the available bandwidth of a particular system. For example, in downhole drilling systems, available bandwidth may be limited by the transmission cable, hardware used to communicate across tool joints, electronic hardware in the nodes 18, the downhole environment, or the like. Thus, the data rate adjustment module 86 may efficiently allocate the limited available bandwidth where it is most needed.

For example, in selected embodiments, most of the network traffic may flow from downhole tools 46 and sensors 44 to the surface for analysis. Thus, ordinarily, most of the network bandwidth may be allocated to traffic traveling uphole. Nevertheless, in some circumstances, more bandwidth may be needed for traffic traveling downhole. For example, in some cases, significant downhole bandwidth may be needed when reprogramming downhole tools 46 and sensors 44, or when sending large amounts of control data downhole. In these instances, the data rate adjustment module 86 may adjust the bandwidth to provide additional bandwidth to downhole traffic. In some instances, this may include reducing the allocated bandwidth for uphole traffic. Likewise, when the need for additional downhole bandwidth has abated, the data rate adjustment module 86 may readjust the available bandwidth by re-allocating bandwidth to uphole traffic.

Referring to FIG. 4, as has been partially explained in the background section of the present application, current telemetry systems, such as mud pulse telemetry, create severe limitations with respect to processing data gathered by downhole sensors, adjusting drilling parameters in response to gathered data, and communicating between downhole tools and sensors and surface personnel and equipment. For example, as was previously explained, various past and current technologies disclosed in the prior art place data processing hardware downhole, near downhole tools and sensors, to process data gathered from these tools and sensors. For example, data processing or logging hardware 90 may be installed in the bottom hole assembly 21 (“BHA”) along with other downhole tools 46 and sensors 44. Nevertheless, because of the extremely slow data rates of mud pulse telemetry, very little raw data is transmitted uphole where it can be logged, analyzed, or used to adjust drilling parameters. To the contrary, before data is transmitted to the surface 19, raw data may be processed and condensed by downhole hardware 90 into “answers” or “conclusions” represented by a relatively small number of data bits. These bits may then be transmitted 96 uphole by way of a pressure transducer 92 that modulates digital data onto pressure pulses that travel up and down the drill string. These pressure pulses may be demodulated at the surface 19 where an operator may analyze the data and take action in response thereto. Nevertheless, large amounts of valuable raw data gathered from sensors and other downhole devices never reach the surface 19, or at least are not transmitted to the surface 19 in real time.

Another problem with prior art systems is that processing hardware 90 may be severely limited in the downhole environment. For example, downhole processors 90 may be limited by conditions such as high temperatures, vibration, corrosive elements, and the like. Thus, processing hardware 90 that is usable in downhole environments may be inferior to high-speed processors that are available in modem day computers, workstations, and the like. Therefore, the quantity and quality of data analysis that is performed downhole may be significantly less than analysis that could be performed at the surface 19, where more sophisticated and higher-performance processing equipment may be available.

In addition, downhole processing hardware 90 may require software or executable code to operate properly and to perform desired tasks. This software or executable code may be modified by reprogramming the hardware to alter or improve the functionality of the hardware 90. Nevertheless, because of the slow downhole data rates of current telemetry systems, such as mud pulse telemetry, reprogramming may be very time-consuming. Thus, the inadequacy of mud pulse telemetry may significantly slow down the downhole drilling process, and limit the capability of downhole hardware 90.

Moreover, the slow data rates of mud pulse and other telemetry systems may also affect the implementation of closed-loop drilling systems. Closed-loop systems use feedback from downhole sensors 46 and other devices to automatically adjust and optimize drilling parameters without operator intervention. For example, a closed-loop system may be used to monitor the position of the drill bit 20 as it penetrates the formation. This position may be compared to a target position that reflects the desired path of the drill string 14. The closed-loop system may then automatically adjust drilling parameters, such as drilling direction, by adjusting downhole-drilling parameters to align the drill sting 14 with the target. This may be done by self-adjusting and without human intervention.

Due to the speed and accuracy of modem-day processors, compared to manual human input, drilling parameters may be adjusted rapidly and accurately in response to changing downhole conditions. Closed-loop systems may help to prevent or reduce undershooting, overshooting, or inaccurate adjustments that are common when manually changing drill string parameters. Moreover, closed-loop drilling systems may require less supervision than manually operated systems, thereby reducing the need for human intervention. This may significantly reduce the expense of operating a drill rig and can reduce the time needed to tap into oil and gas bearing reservoirs.

Nevertheless, mud pulse telemetry severely limits the way close-loop systems may be implemented in a drilling system. For example, due to the limited bandwidth of mud pulse telemetry, control circuitry 88 used to automatically adjust drill string parameters is typically installed downhole near downhole sensors 44 and tools 46. In certain cases, some secondary control 94 may be provided from the surface 19. For example, a secondary control module 94 may be used to transmit minor control adjustments 98 to the primary control module 88. In some case, these may simply be manual adjustment made by a drill string operator.

Nevertheless, this secondary control module 94 may be severely limited by the constraints imposed by mud pulse telemetry and may play a minor part in the closed-loop drilling system. This may be undesirable for several reasons. First, the speed and sophistication of control circuitry may be significantly limited in a downhole environment, as was previously explained. Second, because control circuitry 88 is effectively isolated downhole, closed-loop adjustments to drilling parameters may be primarily limited to downhole tools and components. Third, significant data that is used by the control circuitry 88 is not available at the surface 19 for logging, analysis, or use to adjust drilling parameters due to the slow data rates of mud pulse telemetry. Thus, apparatus and methods are needed to overcome many of these limitations.

Referring to FIG. 5, in selected embodiments, a closed-loop drilling system in accordance with the invention may include tools 46 and sensors 44 installed in the bottom hole assembly 21 of a drill string 14. Sensors 44 may be used to gather data and measurements corresponding to downhole conditions. For example, in selected embodiments, downhole tools 46 and sensors 44 may include coring tools, mud logging devices, flow rate sensors, RPM sensors, torque sensors, pore fluid sensors, permeability sensors, density sensors, resistivity sensors, induction sensors, sonic devices, radioactivity sensors, gamma ray tools, electrical potential tools, vibration sensors, magnetic sensors, Hall-effect sensors, temperature sensors, accelerometers, imaging devices, seismic devices, caliper tools, pressure sensors, inclination sensors, azimuth sensors, surveying tools, navigation tools, MWD tools, DWD tools, LWD tools, GPS devices, load sensors, displacement sensors, kick detection sensors, fluid sampling devices, tool-wear sensors, or the like. The tools 46 and sensors 44 may communicate with one or several high-speed network nodes 18 e. Likewise, other high-speed nodes 18 b-d may be located at selected intervals along the drill string. These nodes 18 b-e may communicate with one another and carry raw data 100 in real time from the tools 46 and sensors 44 to the surface 19. Due to the large amount of rate 100 that may be gathered by numerous tools 46 and sensors 44, the downhole network 17 must support a data rate far greater than that supported by mud pulse telemetry.

Since raw data is available in real time at the surface 19, a primary control module 88 and primary processing module 90 for the closed-loop drilling system may be located at the surface 19. The functionality of the control and processing modules 88, 90 may be provided by hardware, software, or a combination thereof located on computers, such as servers, workstation, personal computers, or other computing devices located at the surface 19, near the drilling rig 10, or at locations remote from the drill rig 10. As was previously explained, because most of the control and data processing functions are performed above the surface 19, more sophisticated and higher performance computers and other hardware may be used that would not be adaptable or usable in a downhole environment. Likewise, control and processing functions that were formerly performed downhole may be reduced or eliminated. Or in other embodiments, control and processing circuitry that was previously provided in downhole components may be greatly supplemented or enhanced by the high-speed network 17 and surface control and processing devices 88, 90.

The primary control module 88 may receive raw data 100 and automatically adjust drilling parameters in response thereto. Likewise a processing module 90 may be located at the surface 19 to process the raw data 100 and extract important information concerning downhole conditions. This processed data may also be used by the control module 88 to adjust drilling parameters. Because the functionality of the control module 88 is located primarily at the surface 19, both uphole and downhole drilling parameters may be effectively adjusted. For example, certain drilling parameters, such as drill string RPM, torque, mud rheology, mud pressure, and weight-on-bit, may be adjusted from the surface 19, since these parameters are primarily changed by adjusting surface drilling equipment.

Likewise, the control module 88 may also adjust downhole-drilling parameters by communicating with downhole equipment through the network 17. For example, the control module 88 may adjust downhole parameters such as downhole motor RPM, torque, or weight-on-bit, or may adjust directional drilling tools that steer the drill bit in a desired direction. Because of the large bandwidth of the network 17, the network 17 may support large amounts of control data 102 flowing downhole.

Referring to FIG. 6, in another embodiment, some control 94 and processing (not shown) capability may be retained downhole. These control components 94 may communicate with control and processing hardware 88, 90 at the surface 19 through the high-speed network 17. In selected embodiments, downhole control hardware 94 may primarily control downhole drilling parameters, while surface hardware 88, 90 may primarily control surface drilling parameters. In the event that communication is lost between the surface 19 and downhole equipment, the downhole control module 94 may continue to operate by gathering data from downhole tools 46 and sensors 44 and making adjustments to downhole operating parameters in response to the data. Nevertheless, when uphole and downhole hardware components 88, 90, 94 are communicating properly through the network 17, most of the control and processing functionality 88, 90 may still be provided by hardware and software located above the surface 19.

Referring to FIG. 7, a process 103 for implementing a closed-loop drilling system in accordance with the invention may include initially gathering 104 downhole data. As was previously explained, this may be accomplished using any number of tools 46 and sensors 44 located downhole or above the surface 19. This data may then be transmitted 106 over the downhole network 17. For example, data from downhole tools 46 and sensors 44 may be transmitted to surface control and processing hardware 88, 90 for analysis via the network 17. Once received 108, the data may be analyzed 110. In selected embodiments, data analysis 110 may include analyzing the data to determine 111 downhole conditions or comparing 112 the data to pre-determined targets. For example, downhole conditions may be determined 111 by sensing differences in mud pressure at different points along the drill string. These pressure differences may indicate that accumulations of cuttings or other debris may be blocking off the flow of mud and may be increasing the chances of a stuck pipe. Likewise, navigation sensors, such as GPS devices, may determine the current position of the drill bit. This position may then be compared 112 with target data to determine if the drill bit 20 is following a correct path or if directional adjustments need to be made. The foregoing examples are simply presented by way of example and are not intended to limit the scope of the present invention.

Once the data is analyzed 110, responsive action may be determined 113. For example, responsive action may include adjusting 114 drilling parameters to optimize drilling, to correct undesired conditions, to correct deviations from selected targets, or the like. Drilling parameters may include both uphole parameters 115 and downhole parameters 116. Uphole parameters 115 may be adjusted at the surface 19, whereas downhole parameters 116 may be adjusted downhole through the network 17. Uphole parameters 115 may include parameters such as weight-on-bit, drill string RPM, drill string torque, kick control, drilling fluid flow rate, drilling fluid rheology, drilling fluid pressure, or the like. Likewise, downhole parameters may include parameters such as weight-on-bit, downhole motor RPM, downhole motor torque, drilling direction, drilling fluid jet direction, drilling fluid jet flow rate, drilling fluid flow rate, drilling fluid rheology, drill jarring, kick control, drilling fluid pressure, or the like.

Referring to FIG. 8, in one embodiment, a downhole network 17 in accordance with the invention may include a top-hole node 18 a and a bottom-hole node 18 e. A bottom-hole node 18 e may interface to various components located in or proximate a bottom-hole assembly 21. For example, a bottom-hole node 18 e may interface to a temperature sensor 126, an accelerometer 128, a DWD (diagnostic-while-drilling) tool 130, or other tools 46 c or sensors 44 c such as those listed in the description of FIG. 3.

A bottom-hole node 18 e may communicate with an intermediate node 18 c located at an intermediate point along the drill string 14. The intermediate node 18 c may also provide an interface to tools 46 b or sensors 44 b communicating through the network 17. Likewise, other nodes 18, such as a second intermediate node 18 b, may be located along the drill string 14 to communicate with other sensors 44 a or tools 46 a. Any number of intermediate nodes 18 b, 18 c may be used along the network 17 between the top-hole node 18 a and the bottom-hole node 18 e.

In selected embodiments, a physical interface 122 may be provided to connect network components to a drill string 14. For example, since data may be transmitted directly up the drill string on cables or other transmission media integrated directly into drill pipe 16 or other drill string components, the physical interface 122 may provide a physical connection to the drill string so data may be routed off of the drill string 14 to network components, such as a top-hole node 18 a, or analysis device 28.

For example, a top-hole node 18 a may be operably connected to the physical interface 122. The top-hole node 18 a may also be connected to an analysis device 28 such as a personal computer. The personal computer may be used to analyze or examine data gathered from various downhole tools 46 or sensors 44. Likewise, tool and sensor data 120 a may be saved or output from the personal computer. Likewise, in other embodiments, tool and sensor data may be extracted directly from the top-hole node 18 a for analysis.

Referring to FIG. 9, in selected embodiments, a node 18 may include various components to provide desired functionality. For example switches 42, multiplexers, or a combination thereof may be used to receive, switch, and multiplex or demultiplex signals, received from other uphole 140 a and downhole 140 b nodes 18. The switches 42 or multiplexers may direct traffic such as data packets or other signals into and out of the node 18, and may ensure that the packets or signals are transmitted at proper time intervals, frequencies, or combinations thereof.

In certain embodiments, the multiplexer may transmit several signals simultaneously on different carrier frequencies. In other embodiments, the multiplexer may coordinate the time-division multiplexing of several signals. Signals or packets received by the switch 42 or multiplexer may be amplified and filtered 50, such as to remove noise. In certain embodiments received signals may simply be amplified. In other embodiments, the signals may be received, data may be demodulated therefrom and stored, and the data may be remodulated and retransmitted on a selected carrier frequency having greater signal strength. A modem 40 may be used to demodulate digital data from signals received from the switch 42 or multiplexer and modulate digital data onto carrier signals for transfer to the switches 42 or multiplexer for transmission uphole or downhole

The modem 40 may also perform various tasks such as error-checking 76 and data compression. The modem 40 may also communicate with a microcontroller 134. The microcontroller 134 may execute any of numerous applications 136. For example, the microcontroller 134 may run applications 136 whose primary function is acquire data from one or a plurality of sensors 44 a-c. For example, the microcontroller 134 may interface to sensors 44 such as inclinometers, thermocouplers, accelerometers, imaging devices, seismic data gathering devices, or other sensors such as those listed in the description of FIG. 3. Thus, the node 18 may include circuitry to function as a data acquisition tool.

In other embodiments, the microcontroller 134 may run applications 136 that may control various tools 46 or sensors 44 located downhole. That is, not only may the node 18 be used as a repeater, and as a data gathering device, but may also be used to receive or provide control signals to control selected tools 46 and sensors 44 as needed. The node 18 may also include a volatile memory device 34, such as a FIFO or RAM, that may be used to store data needed by or transferred between the modem 40 and the microcontroller 134.

Other components of the node 18 may include non-volatile memory 36, which may be used to store data, such as configuration settings, node addresses, system settings, and the like. One or several clocks 132 may be provided to provide clock signals to the modem 40, the microcontroller 134, or any other device. A power supply 52 may receive power from an external power source 138 such as batteries. The power supply 52 may provide power to any or all of the components located within the node 18. Likewise, an RS232 port 38 may be used to provide a serial connection to the node circuit 18.

Thus, the node 18 described in FIG. 6 may provide many more functions than those supplied by a simple signal repeater. The node 18 may provide many of the advantages of an addressable node on a local area network. The addressable node may amplify signals received from uphole 140 b or downhole 140 a sources, be used as a point of data acquisition, and be used to provide control signals to desired sensors 44 or tools 46. These represent only a few examples of the versatility of the node 18. Thus, the node 18, although useful and functional as a repeater 30, may have a greatly expanded capability.

Referring to FIG. 10, a packet 142 containing data, control signals, network protocols, or the like may be transmitted up and down the drill string 14 through the network 17. For example, in one embodiment, a packet 142 in accordance with the invention may include training marks 144. Training marks 144 may include any overhead, synchronization, or other data needed to enable another node 18 to receive a particular data packet 142.

Likewise, a packet 142 may include one or several synchronization bytes 146. The synchronization byte 146 or bytes 146 may be used to synchronize the timing of a node 18 receiving a packet 142. Likewise, a packet 142 may include a source address 148, identifying the logical or physical address of a transmitting device, and a destination address 150, identifying the logical or physical address of a destination node 18 on a network 17.

A packet 142 may also include a command byte 152 or bytes 152 to provide various commands to nodes 18 within the network 17. For example, commands 152 may include commands to set selected parameters, reset registers or other devices, read particular registers, transfer data between registers, put devices in particular modes, acquire status of devices, perform various requests, and the like.

Likewise, a packet 142 may include data or information 154 with respect to the length 154 of data transmitted within the packet 142. For example, the data length 154 may be the number of bits or bytes of data carried within the packet 142. The packet 142 may then include data 156 comprising a number of bytes. The data 156 may include data gathered from various sensors 44 or tools 46 located downhole, or may contain control data to control various sensors 44 or tools 46 located downhole. Likewise one or several bytes 158 may be used to perform error checking of other data or bytes within a packet 142. Trailing marks 160 may provide any other overhead or synchronization needed after transmitting a packet 142. One of ordinary skill in the art will recognize that network packets 142 may take on many forms and contain varied information. Thus, the example presented herein simply represents one contemplated embodiment in accordance with the invention, and is not intended to limit the scope of the invention.

The present invention may be embodied in other specific forms without departing from its essence or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes within the meaning and range of equivalency of the claims are to be embraced within their scope. 

1. A closed-loop downhole drilling system, the system comprising: a downhole drilling string; a communications network comprising a plurality of nodes spaced at selected intervals along the downhole drilling string; a sensor, located at a selected point along the downhole drilling string, configured to provide data corresponding to conditions sensed downhole, the sensor being in operable communication with the downhole communications network; and a control module, in operable communication with the communications network, configured to receive the data through the communications network and automatically adjust at least one parameter of the downhole drilling system in response to the data.
 2. The system of claim 1, wherein the plurality of nodes are in operable communication with one another.
 3. The system of claim 1, wherein the sensor is selected from the group consisting of a coring tool, a mud logging device, a flow rate sensor, an RPM sensor, a torque sensor, a pore fluid sensor, a permeability sensor, a density sensor, a resistivity sensor, an induction sensor, a sonic device, a radioactivity sensor, a gamma ray tool, an electrical potential tool, a vibration sensor, a magnetic sensor, a Hall-effect sensor, a temperature sensor, an accelerometer, an imaging device, a seismic device, a caliper tool, a pressure sensor, an inclination sensor, an azimuth sensor, a surveying tool, a navigation tool, an MWD tool, a DWD tool, a LWD tool, a GPS device, a load sensor, a displacement sensor, a kick detector, a fluid sampling device, and a tool-wear sensor.
 4. The system of claim 1, wherein the at least one parameter is selected from a downhole parameter and an uphole parameter.
 5. The system of claim 4, wherein the downhole parameter is selected from the group consisting of weight-on-bit, downhole motor RPM, downhole motor torque, drilling direction, drilling fluid jet direction, drilling fluid jet flow rate, drilling fluid flow rate, drilling fluid rheology, drill jarring, kick control, and drilling fluid pressure.
 6. The system of claim 4, wherein the uphole parameter is selected from the group consisting of weight-on-bit, drill string RPM, drill string torque, kick control, drilling fluid flow rate, drilling fluid rheology, and drilling fluid pressure.
 7. The system of claim 1, wherein the control module is located above the ground's surface.
 8. The system of claim 1, wherein the control module is located below the ground's surface.
 9. The system of claim 1, wherein the communications network supports a data transmission rate of at least 100 bits per second.
 10. The system of claim 1, wherein the data is raw data that is processed above the ground's surface.
 11. A method for implementing a closed-loop downhole drilling system, the method comprising: providing a downhole drilling string; placing a plurality of nodes at selected intervals along the downhole drilling string, wherein the plurality of nodes are in operable communication with one another; sensing a condition at a selected point along the downhole drilling string; communicating data corresponding to the condition by way of the plurality of nodes; receiving the data from the plurality of nodes; and automatically adjusting at least one parameter of the downhole drilling string in response to the data.
 12. The method of claim 11, wherein the condition is selected from the group consisting of formation characteristics, drilling fluid rheology, drill string RPM, drill string torque, acoustical measurements, radioactivity, electrical potential, vibration, magnetic field strength, Hall-effect, temperature, acceleration, displacement, downhole dimensions, pressure, inclination, azimuth, drill string position, load, downhole kicks, weight-on-bit, cutting accumulations, fluid flow rates, and tool condition.
 13. The method of claim 11, wherein the at least one parameter is selected from a downhole parameter and an uphole parameter.
 14. The method of claim 13, wherein the downhole parameter is selected from the group consisting of weight-on-bit, downhole motor RPM, downhole motor torque, drilling direction, drilling fluid jet direction, drilling fluid jet flow rate, drilling fluid flow rate, drilling fluid rheology, drill jarring, kick control, and drilling fluid pressure.
 15. The method of claim 13, wherein the uphole parameter is selected from the group consisting of weight-on-bit, drill string RPM, drill string torque, kick control, drilling fluid flow rate, drilling fluid rheology, and drilling fluid pressure.
 16. The method of claim 11, wherein automatically adjusting further comprises adjusting the at least one parameter from above the ground's surface.
 17. The method of claim 11, wherein automatically adjusting further comprises adjusting the at least one parameter from below the ground's surface.
 18. The method of claim 11, wherein communicating further comprises communicating at a data transmission rate of at least 100 bits per second.
 19. The method of claim 11, further comprising processing the data above the ground's surface.
 20. A closed-loop downhole drilling system, the system comprising: a downhole drilling string; a communications network comprising a plurality of nodes spaced at selected intervals along the downhole drilling string; a sensor, located at a selected point along the downhole drilling string, configured to provide data corresponding to conditions sensed downhole, the sensor being in operable communication with the downhole communications network; and a control module, in operable communication with the communications network, configured to receive the data and automatically adjust at least one parameter of the downhole drilling system in response to the data. 